Covert surveillance using multi-modality sensing
The present specification discloses a covert mobile inspection vehicle with a backscatter X-ray scanning system that has an X-ray source and detectors for obtaining a radiographic image of an object outside the vehicle. The systems preferably include at least one sensor for determining a distance from at least one of the detectors to points on the surface of the object being scanned, a processor for processing the obtained radiographic image by using the determined distance of the object to obtain an atomic number of each material contained in the object, and one or more sensors to obtain surveillance data from a predefined area surrounding the vehicle.
1. A mobile inspection vehicle comprising:
an X-ray scanning system comprising an X-ray source and a plurality of detectors for obtaining a radiographic image of an object located outside the vehicle;
one or more sensors adapted to obtain surveillance data from a predefined area surrounding the vehicle;
a range finder for determining a distance from at least one of the plurality of detectors to an area on a surface of the object and adapted to cause a beam of light to be transmitted to the area on the surface of the object and detect light reflected from the area on the surface of the object; and
a processor configured to process the obtained radiographic image, wherein the processor is configured to apply an intensity correction to the obtained radiographic image based on the determined distance.
2. The covert mobile inspection vehicle as claimed in claim 1 wherein the processor is configured to process the obtained radiographic image by using the determined distance of the object to obtain an atomic number of materials contained in the object.
3. The mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprise at least one of an inorganic scintillation detector, a detector comprising NaI(Tl), an organic scintillator, or a detector comprising polyvinyl toluene and wherein each detector is coupled with one or more light sensitive readout devices.
4. The covert mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprise at least one of CdTc, CdZnTe or HgI.
5. The mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprise HPGe.
6. The mobile inspection vehicle as claimed in claim 1 further comprising at least one of a GPS receiver, a scanning laser, a CCTV camera, an infra-red camera, an audio microphone, a directional RF antenna, a wide-band antenna, a chemical sensor, or a jamming device.
7. The mobile inspection vehicle as claimed in claim 1 wherein the processor is configured to color one or more individual pixels in the obtained radiographic image based on the determined distance of the object and an atomic number of each material contained in the object.
8. The mobile inspection vehicle as claimed in claim 1 wherein the processor is configured to apply a geometric correction to produce a true likeness of a shape of the object based upon the determined distance.
9. The mobile inspection vehicle as claimed in claim 1 wherein the X-ray source comprises an X-ray tube having a cathode-anode potential difference ranging from 160 kV to 320 kV and a tube current ranging from 1 mA to 50 mA for producing a broad spectrum of X-ray energies.
10. The mobile inspection vehicle as claimed in claim 1 wherein the processor is configured to determine an atomic number of each material contained in the object by determining a boundary of each region of the obtained radiographic image, calculating a deviation of energies of pixels present in each region; calculating a function of the obtained deviation and a function of energies of pixels present in each region, and comparing the calculated function to a pre-determined scale where a first value of the calculated function corresponds to a low Z material and a second value of the calculated function corresponds to a high Z material.
11. The mobile inspection vehicle as claimed in claim 10 wherein the processor is configured to determine the boundary of each region of the obtained radiographic image using a statistical filter.
12. The mobile inspection vehicle as claimed in claim 11 wherein, using the statistical filter, the processor is configured to generate a list of pixel values for each region, rank the pixel values in order, determine a mean of energies of the pixels present in each region, and determine a standard deviation of energies of the pixels present in each region.
13. The mobile inspection vehicle as claimed in claim 1 wherein the X-ray source is configured to generate a focal spot having a diameter in a range of 1 mm to 10 mm.
14. The mobile inspection vehicle as claimed in claim 1 further comprising an automated detection processor configured to integrate and analyze surveillance data from the one or more sensors and send threat items obtained by analyzing the surveillance data for review to an operator via wired or wireless connection.
15. The mobile inspection vehicle as claimed in claim 14 further comprising a transmitter configured to broadcast the surveillance data to a remote location in real time.
16. The mobile inspection vehicle as claimed in claim 1 wherein the one or more sensors comprise a GPS receiver and wherein the processor is configured to process an output of the GPS receiver to determine a location at which each scan line of the obtained radiographic image is generated.
17. The mobile inspection vehicle as claimed in claim 1 wherein the one or more sensors comprise a CCTV camera and wherein the processor is configured to analyze images from the CCTV camera to obtain license plate data.
18. The mobile inspection vehicle as claimed in claim 1 wherein the one or more sensors comprise an infra-red camera and wherein the processor is configured to analyze images from the infra-red camera to identify explosive devices.
19. The mobile inspection vehicle as claimed in claim 1 wherein the processor is configured to apply an intensity correction to the obtained radiographic image based on the determined distance by causing an intensity of the obtained radiographic image of the surface of the object located at a distance greater than a predefined distance to be increased by a predefined factor.
20. The mobile inspection vehicle as claimed in claim 19 wherein the processor is configured to apply an intensity correction to the obtained radiographic image based on the determined distance by causing an intensity of the obtained radiographic image of the surface of the object located at a distance less than the predefined distance to be reduced by a predefined factor.